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 A145181 Continued cotangent recurrence a(n+1)=a(n)^3+3*a(n) and a(1)=7 10
 7, 364, 48229636, 112186849649044142700364, 1411971263214164889494039458947084336929208169473485667118006013929636 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS General formula for continued cotangent recurrences type: a(n+1)=a(n)3+3*a(n) and a(1)=k is following: a(n)=Floor[((k+Sqrt[k^2+4])/2)^(3^(n-1))] k=1 see A006267 k=2 see A006266 k=3 see A006268 k=4 see A006267(n+1) k=5 see A006269 k=6 see A145180 k=7 see A145181 k=8 see A145182 k=9 see A145183 k=10 see A145184 k=11 see A145185 k=12 see A145186 k=13 see A145187 k=14 see A145188 k=15 see A145189 LINKS FORMULA a(n+1)=a(n)^3 + 3*a(n) and a(1)=7 a(n)=Floor[((7+Sqrt[7^2+4])/2)^(3^(n-1))] MATHEMATICA a = {}; k = 7; Do[AppendTo[a, k]; k = k^3 + 3 k, {n, 1, 6}]; a or Table[Floor[((7 + Sqrt[53])/2)^(3^(n - 1))], {n, 1, 5}] (*Artur Jasinski*) CROSSREFS A006267, A006266, A006268, A006269, A145180, A145181, A145182, A145183, A145184, A145185, A145186, A145187, A145188, A145189 Sequence in context: A082098 A057634 A203706 * A221353 A222870 A270247 Adjacent sequences:  A145178 A145179 A145180 * A145182 A145183 A145184 KEYWORD nonn AUTHOR Artur Jasinski, Oct 03 2008 STATUS approved

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Last modified October 20 21:25 EDT 2019. Contains 328273 sequences. (Running on oeis4.)